Electric transformer-furnace.



v 0. BRICK.

ELECTRIC TRANSFORMER FURNACE.

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APPLICATION FILED D50. 26, 1906.

O. PRlGK.

' ELECTRIC TRANSFORMER FURNACE.

APPLwATIrSN FILED 1130.26. 1906.

wiz ssas -.,J' Xjjim? v Patented Aug. 24, 1909.

3 SHEETSSHEET 2.

O. PRICKQ ELEGTRIU TRANSFORMER FURNACE.

APPLICATION FILED IDEO.26, 1906.

Patented Aug. 24, 1909.

a SHEETS-SHEET 3.

To all whom it may concern:

UNITED STATES PATENT OFFCE.

OTTO FRIGK, OF STOCKHOL M, SWEDEN.

ELECTRIC TRANSFORMER-FURNACE.

Be itknown that. 1. ()'r ro l iucit. a c'itizen of the Kingdom of Sweden. reslding at 'Saltsjiibaden. Stockholm, Sweden, have invented new and useful Improvements in Electric 'lransfoianep Furnaces, of which the following is a specification.

I This inventioirrclates to an improved electric transformer furnace in which the mass to be heated is contained in an annular hearth and is induced by means of a primary coil, the said coil and hearth being arranged on a closed iron core.

The object of the :invention is to provide a transformer furnace having a low self-induction and accordingly a high power factor, so that the size of the generator plant conncctedtothe furnace may be reduced to a minimum. t

The invention consistsazhietly in the combination of ainasonry base with an. annular hearth for the material to be treated form- -ing" the secondary circuit, a primary winding divided in coils placed so as to face more than one side of the hearth, and a closed magnetic core, one lnnb of which is surrounded by the hearth and by the said primary Winding, and the other limbs of which are at such a distance from said winding that a. free space is left between the iron and the primary windirn The invention will be more particularly.

described herebelow with reference. to the accompanying drawings showing several forms of the same. 1

Figure 1 shows a vertical furnace having one coil above and one coil below the hearth. Fig.2 is a horizontal sec- I tion on line IIII inFig. 1. Fig. 3 shows a verticalsection of a furnace in which the.

ner, lower and outer sides. Fig.5 is a verti-,

cal section of a furnace in which the primary winding incloscs the hearth at the inner and lower sides. Fig. 6 shows a furnace in which the primary winding substan tially incloses the hearth.

Referring to Figs. 1 and 2, the furnace has a primary coil 1 above the melting-bath 2 and another primary coil 3 below the same,

while the iron-core is so arranged that no iron' 01: only a small quantity of iron is found n the leaking-fields arising around section of a Specification of Letters Patent. Patented Aug. 24:, 190.).

Application filed December 26, 1906. Serial'No. 349,425.

l the primarvaml secondary circuits. Each .ialt' of the primary \\'indi11gforins a special leakingiield.and as the number ofampereturns in each coil is only the half of that of an undivided winding of the same size and the self-inductionis proportional to the square of the number of turns, the self-induction will, as is easily understood, be reduced to about the half of that of a furnace in other respects, and has an undivided primary winding above or below the hearth, and this will be the case indepe 'idently of the coils beinp connected in series or parallel.

suitably. be so arranged that it can be easily removed in order to make the cover 5 of the ished compared with the arrangementshown in Figs. 1 and 2. the leaking field'within the volume incloscd by' the said cross-section being highly suppressed.

furnace hasa coil (3 inside the inner Wall of the hearth l, another coil 3 below the hearth and a third coil 7 outside the hearth. In this arrangement the cover 5 of the crucible l is freely accessible.

In Fig. 5 is shown a further modification inwhich the coil 7 is dispensed with and in which the coil 3 does not-extend to the full Iwidthof the hearth.

In the furnace shown in Fig. 6 the prin'iarywinding has theshape, of a tube-shaped ring formed by coils 8, 9, 10, 11 and 12, in closing the'crucible t onfall sides, on ac ing-fi'eld nor any self-induction caused thereby exists in the said ar 'angementa The primary winding may in .each'case be divided in an arbitrary number of coils, and especially the parts of the winding above the crucible should be so arranged that they may easily be removed in order to inake'the cover sible.

The coil 1 above the melting-bath should,

marv leal ing-field wi'll'be further dilnin- In the modification shown in Fig. 4 the count whereof practically noiprimary. leakwhich is constructed in analogous manner crucible accessible, and may for said purno of the crucible and the meltingbath acces 1' It will be ,noteddfrom the foregoing that in theen'lbodiinents shown in Figs 3 to 6 the primary \vindin is of channel-shaped cross-section, when t' e term channel is considered in its broad senseas meaning that through which anything passes.

-I am aware that transformer furnaces have been proposedin which the primary circuit is divided in coils arranged above and below the annular hearth, and also that transformer furnaces are known in which areused iron'cores, which are at a-Qomparativelyv great,distance-"from the" primary and --secoi idary circuits and} do not regard such 15 arrangement as novel per-3e, but I v What-I claim and desire to secure by Let tors-Patent, is: i

1. An electric induction furnace comprising a masonry base with an annular hearth for the material to be treated forming the secondary circu'it'of. the furnace, a primary winding fading more than" one side of the hearth, and a closed magnetic core, one limb of which is surrounded by the hearth and by the said primary Winding, and the other limbs of which are at such. distance from said winding that a free space is left hetween the iron and said winding.

2. An electric induction furnace comprisinductive relation to thelheaiithandtlje"pri mar winding, one limb of Which;-core is j 'ing a masonry base having an annular hearth ing a masonry basehaving an annular-hearth surrounded by the hearth and tlie primary winding and the other limbs ,of 'which are I beyond the essential part of the leakage fields of the primary wining and seco'ndary circuit formed'by the hearth. 3

3. An electric induction furnacecomprising a masonry 'base'having an annular hearth for the material to be treated, a primary winding facing three sides of the hearth, and a closed magnetic core in inductive relation. to thehearth and th'eprimary Winding, one

(limb of'whi'ch'core is surrounded by the i hearth and {the primary winding and the other limbs of which are beyond the essential parts of the leakage fields of the primary Winding and secondary circuit formed by the hearth. Y

.4. 'An electric induction furnace, comprisfor the material to be treated,- -'a primary Winding facing all sides of the hearth,,and

va closed magnetic coiei inductive relation to the hearth and the prfmary wlnding, one limb of which core is isurrounded by the hearth and said primany windingand the 0 v other limbs of which are at such-distance fro1n" said Winding that' a free-space isleft between the iron and the primary Winding.

In testimony whereof iI have hereunto-set my hand in: prese'nceoftwo: subscribing wit- 5 nesses'I-Y y a 'OTTQFRLOK. itne'sses-z-i p LUTHER J IDA-RR, STANLEY C. PHILLIPS. 

